Wellington OPP say one woman died after a two-vehicle collision south of Mount Forest on Monday afternoon.
Officers responded to reports of a serious collision involving two SUVs at around 1 p.m. on Highway 6.
Investigators said the drivers, both from Mount Forest, suffered serious injuries.
One driver, a 48-year-old woman, was taken to a local hospital where she was later pronounced dead.
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A 46-year-old man has critical injuries and was airlifted to a trauma centre.
Police said Sideroad 5 and Sideroad 3 were closed into the night as they investigated the cause of the collision.